Bhagavad Gita is a spiritual treatise the contents of which can be understood only by contemplation (indulgence in chintan). There was no other method of indulging in Bhagavad Gita.
Bhagavad Gita can never be taught in schools. The underlying meaning of cosmic precepts of spirituality contained in Bhagavad Gita cannot be understood literally. Prime reason why Gurukul Parampara existed in erstwhile Bharatvarsha (now India)!
In the Gurukul Parampara the student Acharya relationship was that of an enquirer and knower of all. In a gurukul students had lot of time at their disposal to contemplate on vital issues of life contained in various scriptures of Hinduism.
Literary reading of Bhagavad Gita means nothing. The jnana wisdom contained in Bhagavad Gita can never be assimilated that way.
Even in present times even though Gurukul Parampara does not exist, one can indulge in contemplation of one’s own. One can read through the vast expanse of literature relating to enlightened ones like Sri Ramakrishna Paramhansa and Maharshi Ramana. Even though these enlightened souls do not exist in person, but their valuable teachings are available in galore.
Just by mastering art of contemplation human beings can successfully indulge in spirituality contained in Bhagavad Gita. Path of jnana yoga was never about gaining something but understanding cosmic precepts of life contained in Bhagavad Gita, one can cut through darkness of ignorance to become a pure soul atman forever.
Bhagavad Gita was never about cramming something, ritually memorizing shlokas verses. We have to contemplate (indulge in chintan) on the hidden underlying meaning. It took more than seven years of contemplation to understand the difference between Dharma, religion and spirituality. The underlying meaning of spiritual precepts is not that easily understood.